RAJSHAHI, Bangladesh (Reuters) - A rare drought in the middle of the monsoon season is threatening crops that account for up to a third of the country's staple rice output, especially in the north.

Scant rainfall, falling river levels and lack of irrigation have left farmlands barren or sparsely planted, officials said on Wednesday.

Villagers, many too poor to buy irrigation pumps or pay for fuel, were now praying for showers, which weather officials say are unlikely to occur aplenty soon.

Agriculture officials said most lands ready for planting so-called Aman rice would remain uncultivated unless adequate rains fell in the next week or so.

Aman accounts for nearly a third of Bangladesh's annual rice production of 26 million metric tons or more, officials said. Rice is the main staple for Bangladesh's 140 million people.

The monsoon season lasts from June to September in Bangladesh. Rainfall recorded in July this year in the northern Rajshahi division totaled 189 millimeters against 396 a year ago, weather officials said.

They said rainfall across the rest of the country was also down compared with the last monsoon, threatening farming, navigation and fishing and the environment.

"It looks like we are facing a near-drought condition in the middle of the monsoon...this is quite unusual and threatening people's living," said Abdus Sattar, a meteorologist in Rajshahi, 270 km (160 miles) from the capital Dhaka.

Farmers said they were unable to irrigate their land because they lacked pumps or were unable to pay for the fuel they would need. They also now faced a shortage of fertilizer.

"A small patch of land where I planted Aman is now cracking under blazing sun. And I could not manage fertilizer to keep the plants green," farmer Abdur Rahim said.

The Padma river, which often bursts its banks during the monsoon, flooding hundreds of villages and displacing thousands of families, was now flowing far below its normal level for the time of the year.

Abdus Salam, Deputy Director of Rajshahi Divisional Agriculture Extension office, said the situation might improve only if it rained fairly heavily over the next one or two weeks.

Weather officials said the monsoon was playing truant in Bangladesh this year though it was fully active in India and Myanmar.

"I have been waiting and praying for rain that would save my family and everyone who depend so much on agriculture," said Abbur Rahim, a Rajshahi farmer.